Wells Fargo and JPMorgan fell after reporting revenue that was lower than analysts were expecting. JPMorgan and Bank of America led the Dow Jones industrial average lower shortly after the opening bell Friday.
The Dow was down 18 points at 14,848, a loss of 0.1 percent. It had gained 300 points over the previous four days.
The Standard & Poor's 500 was down four points, or 0.3 percent, to 1,588. The Nasdaq composite was down six points, or 0.2 percent, at 3,293.
M&T Bank slumped after saying it would need to delay its merger with Hudson City Bancorp after the Federal Reserve raised concerns about its compliance with bank secrecy and money-laundering rules.